title: Fragmentation of neutral amino acids and small peptides by intense, femtosecond laser pulses.
abstract: High power femtosecond laser pulses have unique properties that could lead to their application as ionization or activation sources in mass spectrometry. By concentrating many photons into pulse lengths approaching the timescales associated with atomic motion, very strong electric field strengths are generated, which can efficiently ionize and fragment molecules without the need for resonant absorption. However, the complex interaction between these pulses and biomolecular species is not well understood. To address this issue, we have studied the interaction of intense, femtosecond pulses with a number of amino acids and small peptides. Unlike previous studies, we have used neutral forms of these molecular targets, which allowed us to investigate dissociation of radical cations without the spectra being complicated by the action of mobile protons. We found fragmentation was dominated by fast, radical-initiated dissociation close to the charge site generated by the initial ionization or from subsequent ultrafast migration of this charge. Fragments with lower yields, which are useful for structural determinations, were also observed and attributed to radical migration caused by hydrogen atom transfer within the molecule.
authors.affiliation: Centre for Plasma Physics, School of Mathematics and Physics, Queen's University Belfast, Belfast, UK.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Duffy
authors.forename: Orla
authors.initials: O
authors.lastname: Kelly
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Calvert
authors.forename: Raymond B
authors.initials: RB
authors.lastname: King
authors.forename: Louise
authors.initials: L
authors.lastname: Belshaw
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Kelly
authors.forename: John T
authors.initials: JT
authors.lastname: Costello
authors.forename: David J
authors.initials: DJ
authors.lastname: Timson
authors.forename: William A
authors.initials: WA
authors.lastname: Bryan
authors.forename: Thomas
authors.initials: T
authors.lastname: Kierspel
authors.forename: I C Edmond
authors.initials: IC
authors.lastname: Turcu
authors.forename: Cephise M
authors.initials: CM
authors.lastname: Cacho
authors.forename: Emma
authors.initials: E
authors.lastname: Springate
authors.forename: Ian D
authors.initials: ID
authors.lastname: Williams
authors.forename: Jason B
authors.initials: JB
authors.lastname: Greenwood
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D007834:Lasers; D013058:Mass Spectrometry / Q000379:methods*; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D007477:Ions; D010455:Peptides